What type of immunity results from the body's production of antibodies in response to an antigen?

• A. Passive immunity
• B. Active immunity
• C. Innate immunity
• D. Acquired immunity

Answer: (B)

Active immunity is the type of immunity that arises when the body produces its own antibodies in response to exposure to an antigen. This can occur naturally, such as when an individual is infected by a pathogen and the immune system generates antibodies to fight off the infection. Additionally, it can occur artificially, as seen with vaccinations where a harmless form of the antigen is introduced into the body to stimulate the immune response without causing the disease.

When antibodies are produced by the body's immune system in response to an antigen, the individual gains long-lasting protection against that specific pathogen. This immunity is considered "active" because it requires the immune system to actively engage in the process of generating antibodies and developing memory cells.

Other types of immunity, such as passive immunity, involve the transfer of antibodies from another source rather than the individual's own immune system generating them. Innate immunity refers to the immediate, non-specific defenses that are in place from birth. Acquired immunity is a broader term that can encompass both active and passive immunity but is often used interchangeably with active immunity, which specifically pertains to the generation of antibodies in response to antigens. In this context, active immunity specifically highlights the role of the individual’s immune response rather than external sources of antibodies.